The present invention relates generally to devices that provide a tactile interface with the relative position of the probe of a cantilever-based force measurement instrument, such as an atomic force microscope, molecular force probe or profilometer, or the force between the probe and a sample.
Cantilever-based force measurement instruments are now commonly used to make measurements with micro-newton to pico-newton resolution on a variety of samples, including single molecules. In many cases it is advantageous to provide feedback to the operator as to the relative position of the probe of the cantilever or the force between the probe and the sample. This has been accomplished a number of ways, including the use of visual and audio signals.
It has also been accomplished through tactile feedback where a force or torque is applied to a control mechanism that is related to another signal, such as the deflection of the cantilever probe. There are a number of such haptic devices that already exist for the control of cantilever-based force measurement instruments including a joystick developed by Hermann Gaub of the University of Munich and a joystick based on commercially available force feedback joysticks developed at MDT-NT, a Russian nanotechnology company. The three-dimensional haptic interface marketed by 3rd Tech in North Carolina goes even further by extending the force feedback to three dimensions.
It is desirable to have a tactile feedback device that is simple and that could be easily incorporated into existing control electronics or that could be incorporated into a relatively small and simple hand-held device. We have developed a force feedback knob. In this device, a parameter, such as the voltage applied by the instrument's piezo or the setpoint or desired position of the instrument's closed loop positioner, is varied by rotating the knob. A variable torque is applied to the knob to provide tactile feedback to the operator regarding the value of an appropriate parameter, such as the deflection of the cantilever probe.